It's good that you want to be sure about your supplier, I guess there is nothing wrong with your plan of checking with eBay about it. Generally, you should be sure that your supplier is selling only authentic products otherwise you might get in trouble or your listing may be removed.
There are 3 ways which you can contact eBay, via phone, email or live chat. Please note that the time difference may affect the availability of their contact support. To learn more about how you can reach eBay please go to Link hidden: Login to view
Hope this help, cheers :)